CARLSBAD, N.M. (AP) — It’s been more than two decades since a discovery this big has been made at Carlsbad Caverns National Park in southeastern New Mexico.

Park officials announced this week that a new room has been discovered high in the ceiling of the main cavern. It was found on Halloween night by Derek Bristol, a caver and volunteer with the Cave Research Foundation, and Shawn Thomas, a cave technician at the park.